Intermittent timeout in /html/semantics/embedded-content/media-elements/autoplay-allowed-by-permissions-policy.https.sub.html

```
TIMEOUT /html/semantics/embedded-content/media-elements/autoplay-allowed-by-permissions-policy.https.sub.html

    TIMEOUT [expected PASS] subtest: Permissions-Policy header: autoplay * allows same-origin iframes.

    Test timed out
```